Controlling Power Saving Mode In Radio

ABSTRACT

The disclosure relates to controlling the operational mode of a radio in a wireless device, with an aim to reducing power consumption. A method of controlling the operational mode of a radio in a wireless device, includes executing at least one application, that provides access information for use by radio control logic to determine an operational mode of a radio, where the said access information defines usage of the radio by that application.

FIELD OF THE INVENTION

The present invention relates to controlling the operational mode of aradio in a wireless device, with an aim to reducing power consumption.

BACKGROUND OF THE INVENTION

As is known, for wireless communication in a cellular network, thenetwork includes base stations which manage communications betweenmobile devices. According to the long term evolution (LTE) Standardsdeveloped as part of the 3GPP Standard, a mechanism has been introducedin an attempt to save power at the mobile devices. There is an ongoingrequirement to reduce power consumption of such mobile devices as thequantity of data transmitted over the wireless network steadilyincreases. According to the approach adopted in the LTE Standard, awireless device can initiate a discontinuous reception (DRX) and/ordiscontinuous transmission (DTX) which allows it to turn the radio to asleep state for long periods, based on some predetermined inactivitytimer values negotiated with the base station. In the LTE Standard, thebase station is referred to as an e Node B (eNB).

However, these inactivity timer values are too generic and cannot takeinto account specific network traffic activity occurring at the wirelessdevice at any given time.

It is an aim of the present invention to enhance power saving for aradio access device.

SUMMARY OF THE INVENTION

According to an aspect of the present, there is provided a method ofcontrolling the operational mode of a radio in a wireless device, themethod comprising:

-   -   executing at least one application, said application providing        access information for use by radio control logic to determine        an operational mode of a radio, wherein said access information        defines usage of the radio by that application.

A further aspect of the invention provides a computer program productcomprising program code means constituting an application which whenexecuted by a processor provides access information for use by radiocontrol logic to determine an operational mode of a radio, wherein saidaccess information defines usage of the radio by the application.

A further aspect of the invention provides a wireless device comprising:

-   -   a radio for communicating over a wireless channel;    -   a processor arranged to execute at least one application        requiring communication via the radio, wherein when executed,        the application provides access information for use by radio        control logic to determine an operational mode of the radio,        wherein said access information defines usage of the radio by        that application.

Another aspect of the invention provides a method comprising theoperational mode of a radio in a wireless device, the method comprising:

-   -   executing at least one application, said application generating        at least one type of data for transmission from the wireless        device using the radio, the data being output to radio control        logic for transmission at intervals determined by the        application;    -   determining the type of data generated for transmission; and    -   the application adjusting the interval based on the type of        data.

Another aspect of the invention provides a wireless device comprising:

-   -   a radio for communication over a wireless channel; and    -   a processor arranged to execute at least one application        requiring communication via the radio, wherein, when executed,        the application is configured to generate at least one type of        data for transmission from the wireless device using the radio,        the data being output to radio control logic for transmission at        intervals determined by the application, the application further        configured to determine the type of data generated for        transmission and to adjust the interval based on the type of        data.

Another aspect of the invention provides a computer program productcomprising program code means constituting an application which whenexecuted by a processor generates at least one type of data fortransmission using a radio, the data being output for transmission atintervals determined by the application, the application furtherdetermining the type of data generated for transmission and adjustingthe interval based on the type of data.

For a better understanding of the present invention and to show how thesame may be carried into effect, reference will now be made by way ofexample of to the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a schematic illustration of a wireless device in communicationwith a network;

FIG. 2 is a schematic description of layers in a protocol stack;

FIG. 3 is a schematic diagram of an application layer communicating witha MAC layer;

FIG. 4 is schematic diagram of an architecture for providing accessinformation between an application layer and a MAC layer;

FIG. 5 is a schematic diagram of a first architecture for implementing ameta-application; and

FIG. 6 is a schematic diagram of a second architecture for implementinga meta-application.

A wireless device is illustrated schematically in FIG. 1. The wirelessdevice 1 includes a microprocessor 2 which executes programs in the formof code which can be held locally in the microprocessor 2 or in a memory4 connected to it. The mobile device 1 has a radio access chip 6 fortransmitting and receiving radio frequency (RF) communications, forexample, between the mobile device 1 and a network 8. The mobile device1 has a power supply which can be in the form of a battery 10 which isillustrated, and/or a connection to an external power supply (notshown).

It would be apparent that the mobile device can include many otherelements which are not illustrated because they are not germane to thepresent context.

RF communications between the mobile device 1 and the network 8 takeplace by transmitting and receiving RF signals over radio channels bythe radio access chip 6. When transmitting or receiving over a channel,the radio needs to be powered on. However, when the radio is not beingused, it can be powered down or enter a power saving mode to reduce thepower consumption of the device 1.

The invention will now be described in the context of a wireless deviceof the type discussed in relation to FIG. 1. The wireless device can beany piece of user equipment (UE) which supports at least one radioaccess technology, for example, UMTS, HSDPA, Wimax, LTE or Wifi.Software for execution by the processor is organised in a protocol stackof the type illustrated in FIG. 2. FIG. 2 illustrates only one exampleof a stack—there are many variations currently in use and the inventioncan be applied in any type of stack. The stack exemplified in FIG. 2includes an application layer 12, a transport layer 14, an Internetlayer 16 and a link layer 18. The link layer is subdivided into aphysical link layer 20 and a media access control (MAC) layer 22.

The link layer is responsible for organising communication technologiesfor the device 1. The media access control layer 22 within the linklayer 18 is responsible for addressing, assigning multiple channels todifferent users and avoiding collisions, amongst other things. Inparticular, it is responsible for controlling the operational mode ofthe radio. It contains a buffer for queuing data to be transmitted andcontrol logic, discussed more fully later. Each layer can communicatewith its equivalent layer in a different wireless device—the link layer18 communicates with a corresponding link layer in a different device atthe level of RF data in the form of frames. Frames are transmitted andreceived over a channel between the radio access chip 6 and the network8, each access requiring the radio device to be powered on. An “access”denotes a state in which the radio access chip is in communication withthe network 8 or another device such that data can be transmitted and/orreceived. According to LTE Standard implementing DRX/DTX as discussedabove, if the link layer had not sent anything for the negotiated timeinterval, the radio may have powered down or entered into a power savingmode.

This could have the effect that the radio is powered down or enters apower saving mode just before a next access, for example, an attempt totransmit frames over the channel by the media access control layer. Thiscan result in unnecessary switching between operational modes of theradio. Further, each time the radio “wakes up” it advises the node 8 orbase station, so unnecessary mode changes can cause an increase insignalling overhead to the node B or base station.

Embodiments of the invention provide an improvement over thisarrangement as described in the following. First, however, the otherlayers in the stack will be described.

The Internet layer provides Internet communications in the form ofpackets carrying IP (Internet Protocol) data with IP headers, and isresponsible for IP addressing.

The transport layer 14 runs host to host communications according to thetransmission control protocol (TCP) or a user datagram protocol (UDP),for example. In this context, a host is any kind of user equipmentseeking to communicate wirelessly.

The application layer 12 handles application-based interactions on aprocess-to-process level between communicating hosts. It is this layerthat runs user applications which may generate data to be transmittedover the channel. Thus, embodiments of the invention are described inthe context that a user equipment runs at least one application thatconnects to the Internet 8 through at least one of the radio accesstechnologies through the media access control layer 22.

The invention can be used with a number of different applications, butone particular context concerns social communications, such as VoIP(Voice over Internet Protocol) calls between UE's, instant messaging(IM) chat or live meetings run over a conference framework. Alongsidethese kind of services, applications can be responsible for datatransfer, such as file transfer, updating presence information forcontacts in a social network, or control data such as “keep-alive” data.References to applications running in the application layer in thepresent case are considered to encompass all such possibilities.

In the described embodiments of the invention, an application running inthe application layer 12 notifies the MAC layer 22 about anticipatedfuture data transmission or receptions. This allows the MAC layer toadapt its radio power saving schedule to the application's channelaccess. The MAC layer has a power saving schedule comprising differentoperational modes including power saving modes, such as sleep, idle,DRX/DTX. By notifying the MAC layer 22 of planned channel access, anumber of advantages can be achieved. First of all, power saving modescan be entered immediately when an application has finished withouthaving to wait for a time-out mechanism to activate the power savingmode. This saves power. Secondly, the MAC layer can suspend powersaving, or avoid going into a deeper power saving mode (e.g., from“sleep” to idle”), if the application reports activity in the nearfuture. This is useful because it may take time and power to wake up theradio from a power saving mode.

One embodiment of the invention will be described with reference to FIG.3. In this embodiment, an application 30 running in the applicationlayer has two basic states: an active state in which it needs constantradio access, and an inactive state where it does not. As examples,consider communication sessions in applications such as IM chat, VoIPcalls, live meeting. An inactive state denotes the end of a currentapplication session. Whenever the application 30 switches from theactive state to the inactive state, it generates a notification 32 tonotify the MAC layer 22 of the inactive state to allow the MAC layer 22to go into a power save mode immediately. As one option, it can send aDRX trigger message to the base station eNB. The MAC layer 22 includescontrol logic 34 which is arranged to receive notifications from aplurality of applications running in the application layer and todetermine if a situation arises when all such applications are inactive.If so, the control logic 34 causes the MAC layer 22 to adopt a powersave mode 36. If there remain applications which are active, thedecision logic 34 causes the MAC layer to adopt a stay awake mode 38 forthe radio.

When going from inactive to active, an application may notify the MAClayer 22 explicitly, or simply provide data to it.

Determining if an application is entering an inactive state is notnecessarily straight forward. In a situation where an applicationcomprises a number of parallel services which are typically notcoordinated, an application can monitor all of its services beforesending an “inactive” notification 32. As an example, a VoIP applicationmay end one service, a call where a user hangs up, but another service,for example, presence information updating, starts shortly after. Aninactive state of a VOIP application can be determined for example inone of the following states: (i) at the end of a call; (ii) whenpresence synchronisation is complete; and (iii) when file transfer iscomplete.

Alternatively, to allow the radio to go into power save mode, theapplication may choose to suspend non-essential services if itdetermines that only non-essential services are running. Additionally,this decision can take battery status information (obtained via theoperating system) in account, so that non-essential services aresuspended only when battery level is below a certain threshold.

In another embodiment of the invention, an application sends data atperiodic (regular) intervals. For example, this could be keep alive datato avoid losing a connection to an external network if the device 1 sitsbehind a firewall. Another example is sending data at the audio codecframe rate in a Voice over IP application. The application notifies theMAC layer 22 about the periodicity and updates this every time itchanges. If the application is running multiple services, to maintainperiodicity, it may buffer data produced by one or more services totransmit it in synchronicity with another service that is producing dataperiodically. Information about periodicity can be supplied from anumber of applications running in the application layer 12. Thisinformation is received by control logic 34 in the MAC layer 22. Thecontrol logic can estimate, from the periodicity and the last time theapplication sent data, the time until the next anticipated datatransmission from that application. By combining these times for allapplications, the time t_(est) until any of the applications will senddata can be estimated. control logic 44 can use the estimated timet_(est) to decide whether it is worthwhile to switch into a power savemode 36 or to stay in a stay awake mode 38.

In particular, the MAC layer 22 can use the periodicity information in anumber of ways. It can be used to understand which DRX/DTX cycle shouldbe triggered, assuming that the wireless device is provided with optionsto make such a selection. Additionally and alternatively, it can be usedby the wireless device to delay getting into idle mode by using a higherinactivity timer setting for idle mode. This is because it already knowsthat the idle mode would be interrupted by the next message from theapplication and would result in excessive signalling overhead due tonetwork re-entry and a long DTX/DRX cycle instead may result in betterpower savings. Thus, this allows the wireless device to save power aswell as signalling overhead.

An application may optimise use of such a mechanism by adapting theintervals at which it sends data to reduce the amount of time that theMAC layer requires the radio to be active. Assume that when the MAClayer places the radio in a stay awake (active) mode, it will remainactive for a period of X milliseconds. If the application sends data atintervals Y milliseconds with Y>X, the radio will be awake X/Y of thetime. Therefore, by increasing Y the awake time—and thus powerconsumption—can be decreased significantly. This is not the case for asystem such as that described in the introductory part with reference tothe CTE implemented DRX/DTX mechanism where power saving is based ontime-outs because these time-outs have to be reasonably large (>Y) toavoid excessive power save mode switching when transmissions are notperiodic. In such a situation, increasing Y would only lead to a higherdelay but little power saving. If the data is real time data such asaudio data transmitted during a call, Y may only be increased to athreshold value without causing audible delay in the receive signal.

If the transmission of data is not real time, such as file transfer, itmay still be necessary to limit the transmission interval, so as not tooverload the transmission buffer in the MAC layer 22.

The application may therefore determine the type of data that is beingsent and apply a predefined interval between transmitting data to theMAC layer 22. The predefined interval will be dependent upon the type ofdata that is being sent. The interval need not be a function of the typeof data alone, but may take other parameters into account as well. Forexample, return trip time (RTT) or knowledge about the MAC layer buffersize can be taken into account.

FIG. 4 illustrates an architecture by means of which access informationcan be supplied from the application layer 12 to the MAC layer 22. FIG.4 illustrates three applications, App1, App2, App3 running in theapplication layer and an application interface (API) which can beimplemented for example, in the operation system of the wireless device.When an application has access information to supply to the MAC layer,it calls a function from the API which function allows data to be storedin a manner accessible by the API. This information can be supplied tothe MAC layer 22 on request by the MAC layer control logic 34, or in anyother appropriate way.

The architecture of FIG. 4 is also applicable to the following describedembodiments of the invention.

According to another embodiment of the invention, an application runningin the application layer notifies the MAC layer 22 about its currentreal time constraints. That is, a message 50 is passed from theapplication indicating the real time constraints or delay tolerance ofthe application. This is supplied to control logic 34 to decide if theradio should be in power save mode 36 or wake up mode 38. When a radiois in power save mode and data is received from the application layer,the radio can either wake up to send the data immediately, or it canstay in power save mode and wait for more data to transmit all in onego. The latter is more power efficient because it leads to more time inthe power save mode and less switching between modes. On the other hand,for real time data such as in a VoIP application, the induced waitingtime may degrade conversation quality. By providing the real timeconstraints/delay tolerance from the application to the MAC layer, theMAC layer can make a more informed decision in control logic 34 as towhether or not to switch out of the power saving mode.

Real time constraints can change over time for different reasons. Forexample, even a VoIP application which is not currently running a callwill often be transmitting data to avoid losing a network connection, toupdate presence information for contacts or to run other services suchas file transfer. All such data has no real time constraints, so as longas only this type of services are running, the MAC layer should benotified of a high delay tolerance. Moreover, it is known thatconversation degradation does not increase linearly with the round triptime (RTT) but rather exponentially. Therefore the application maydetermine the delay tolerance in dependence on RTT. For example, if thecurrent RTT is very low, adding a few tenths of milliseconds to it willhave only little impact on conversation quality and is thus acceptableto reduce power consumption. If the application is running multipleservices (S) the real time constraints for these services should beaggregated into one. Preferably, the strictest real time constraint isused.

Round trip time is a known transmit delay parameter which can bedetermined in a number of different ways. For example, the transmissiontime for a packet (“timestamp”) can be added to its payload. Thereceiver will then extract this timestamp and return it to thetransmitter in another packet, after which the transmitter can estimatethe RTT as the difference between the reception time of the fed backpacket and the timestamp.

The above embodiments of the invention can be implemented using aspecialised meta-application designed to interoperate with the MAC layer22. The meta-application provides a specialised way of communicatinginformation from a plurality of applications to the MAC layer. Onearchitecture is illustrated in FIG. 5. According to this architecture, aplurality of applications App1, App2 . . . AppN register with ameta-application MA. The meta-application can run in the operatingsystem. The meta-application handles data coming from all of theapplications and provides that data to a socket 23 on the MAC layer 22.The meta-application includes an access information combiner 52 whichcombines access information of the type discussed above and supplies itto the MAC layer 22. In this architecture, all communications betweenthe application layer and the MAC layer are handled by themeta-application. This can be done through an API as described withreference to FIG. 4.

FIG. 6 illustrates an alternative architecture where each applicationApp1, App2 . . . AppN communicates its data to the MAC layer 22 byindividual IP sockets 23 1, 23 2 . . . 23 N. Access information issupplied from each application to the meta-application MA, whichsupplies combined access information to the MAC layer 22. In thisarchitecture, the applications run a negotiation of MAC access frequencyand timing/phase point with the meta-application, based on which themeta-application informs the MAC layer. The meta-application informs theMAC layer about activity/inactivity and periodicity that allapplications will subsequently adhere to in their operation.

In the embodiment discussed above where the access information isperiodicity, the periodicity of a number of applications may be comparedin the meta-application. The meta-application can then report thecombined periodicity of the applications to the MAC layer 22. Forexample, two applications may each connect to the Internet every tenseconds, wherein the applications are half a circle out of phase. Inthis case, the meta-application will determine that the combined rate atwhich the applications connect to the Internet is every five seconds.This is reported to the MAC layer 22 such that the MAC layer can thencontrol when the radio should go into an inactive state.

Any application running on the user equipment can register on themeta-application. In this way, all the registered applications can beconsidered as services running within the meta-application.

It should be understood that the block, flow, and network diagrams mayinclude more or fewer elements, be arranged differently, or berepresented differently. It should be understood that implementation maydictate the block, flow, and network diagrams and the number of block,flow, and network diagrams illustrating the execution of embodiments ofthe invention.

It should be understood that elements of the block, flow, and networkdiagrams described above may be implemented in software, hardware, orfirmware. In addition, the elements of the block, flow, and networkdiagrams described above may be combined or divided in any manner insoftware, hardware, or firmware. If implemented in software, thesoftware may be written in any language that can support the embodimentsdisclosed herein. The software may be stored on any form ofnon-transitory computer readable medium, such as random access memory(RAM), read only memory (ROM), compact disk read only memory (CD-ROM),flash memory, hard drive, and so forth. In operation, a general purposeor application specific processor loads and executes the software in amanner well understood in the art.

While this invention has been particularly shown and described withreferences to example embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1. A method of controlling the operational mode of a radio in a wirelessdevice, the method comprising: executing at least one application, saidapplication providing access information for use by radio control logicto determine an operational mode of a radio, wherein said accessinformation defines usage of the radio by that application.
 2. A methodaccording to claim 1, wherein the step of providing access informationcomprises: calling a function in an application program interface andsupplying said access information to the called function.
 3. A methodaccording to claim 1, wherein a meta-application receives accessinformation from said at least one application and provides accessinformation for use by the radio control logic.
 4. A method according toclaim 3, wherein the meta-application receives access information from aplurality of applications and processes it to provide consolidatedaccess information for use by the radio control logic.
 5. A methodaccording to claim 4, wherein each application separately supplies datafor transmission using the radio to a radio access control function. 6.A method according to claim 4, wherein each application supplies datafor transmission using the radio to the meta-application, which suppliessaid data to a radio access control function.
 7. A method according toclaim 1, wherein the access information comprises a notificationidentifying a switch between an active and an inactive state of theapplication.
 8. A method according to claim 7, wherein the at least oneapplication provides a plurality of services, the application monitoringthe plurality of services to determine when to issue said notification.9. A method according to claim 1, wherein the access informationcomprises periodicity of data transmission.
 10. A method according toclaim 9, wherein the application provides a plurality of services, andwherein data of at least some of said services are buffered in order tobe transmitted in synchronicity with another service that is generatingdata periodically.
 11. A method according to claim 9, wherein theapplication determines the type of data to be transmitted and adjusts aperiodic interval for transmitting said data based on the type of data.12. A method according to claim 11, wherein the periodic interval isadjusted based on transmit delay parameters.
 13. A method according toclaim 1, wherein the access information comprises a level of delaytolerance.
 14. A method according to claim 13, wherein the applicationadjusts the level of delay tolerance based on at least one transmitdelay parameter.
 15. A method according to claim 13, wherein theapplication provides a plurality of services, and the level of delaytolerance which is provided as access information depends on the currentservice being provided by the application.
 16. A method according toclaim 8 wherein the application suspends non-essential services if itdetermines that only non-essential services are running.
 17. A methodaccording to claim 7, wherein the application suspends non-essentialservices if it determines that only non-essential services prevent theinactive state.
 18. A method according to claim 17, wherein anapplication determines whether to suspend non-essential services bytaking into account battery status.
 19. A method according to claim 7,wherein said notification is generated by a VOIP application in at leastone of the following states: (i) at the end of a call; (ii) whenpresence synchronisation is complete; and (iii) when file transfer iscomplete.
 20. A computer program product comprising program codeembodied on a non-transitory computer readable medium which whenexecuted by a processor provides access information for use by radiocontrol logic to determine an operational mode of a radio, wherein saidaccess information defines usage of the radio by the application.
 21. Awireless device comprising: a radio for communicating over a wirelesschannel; a processor arranged to execute at least one applicationrequiring communication via the radio, wherein when executed, theapplication provides access information for use by radio control logicto determine an operational mode of the radio, wherein said accessinformation defines usage of the radio by that application.
 22. Awireless device according to claim 21 comprising an application programinterface, wherein the application is configured to call a function inthe application program interface and supply said access information tosaid function.
 23. A wireless device according to claim 21 wherein theprocessor is arranged to execute a plurality of applications and a metaapplication configured to receive access information from the pluralityof applications and to process said access information to provideconsolidated access information for use by the radio control logic. 24.A method comprising the operational mode of a radio in a wirelessdevice, the method comprising: executing at least one application, saidapplication generating at least one type of data for transmission fromthe wireless device using the radio, the data being output to radiocontrol logic for transmission at intervals determined by theapplication; determining the type of data generated for transmission;and the application adjusting the interval based on the type of data.25. A method according to claim 24 wherein the interval is adjustedbased on transmit delay parameters.
 26. A method according to claim 25wherein one of the transmit delay parameters is round trip time.
 27. Awireless device comprising: a radio for communication over a wirelesschannel; and a processor arranged to execute at least one applicationrequiring communication via the radio, wherein, when executed, theapplication is configured to generate at least one type of data fortransmission from the wireless device using the radio, the data beingoutput to radio control logic for transmission at intervals determinedby the application, the application further configured to determine thetype of data generated for transmission and to adjust the interval basedon the type of data.
 28. A wireless device according to claim 27 whereinthe type of data is selected from real time data and non real time data.29. A computer program product comprising program code embodied on anon-transitory computer readable medium which when executed by aprocessor generates at least one type of data for transmission using aradio, the data being output for transmission at intervals determined bythe application, determines the type of data generated for transmissionand adjusts the interval based on the type of data.